Bibliography (13):

1. What Number Comes Next? The Encyclopedia of Integer Sequences Knows. The ‘Mathematical Equivalent to the FBI’s Voluminous Fingerprint Files’ Turns 50 This Year, With 362,765 Entries (And Counting)

2. https://oeis.org/A001006

3. https://oeis.org/

4. A000108

5. https://oeis.org/A006577

6. Wikipedia Bibliography:

   1. https://en.wikipedia.org/wiki/Motzkin_numbers

      https://en.wikipedia.org/wiki/Motzkin_numbers

   2. On-Line Encyclopedia of Integer Sequences

   3. https://en.wikipedia.org/wiki/Fibonacci_sequence

      https://en.wikipedia.org/wiki/Fibonacci_sequence

   4. https://en.wikipedia.org/wiki/Catalan_number

      https://en.wikipedia.org/wiki/Catalan_number

   5. https://en.wikipedia.org/wiki/Permutation_group

      https://en.wikipedia.org/wiki/Permutation_group

   6. Collatz conjecture

   7. On-Line Encyclopedia of Integer Sequences § Self-referential sequences

      https://en.wikipedia.org/wiki/On-Line_Encyclopedia_of_Integer_Sequences#Self-referential_sequences

   8. On-Line Encyclopedia of Integer Sequences § Sloane’s gap

      https://en.wikipedia.org/wiki/On-Line_Encyclopedia_of_Integer_Sequences#Sloane%27s_gap